1. Field of the Invention
The present invention relates to a thin-film magnetic head element used for recording/reproducing the magnetic head to a magnetic recording medium, especially to a thin-film magnetic head element which has the optimum shape of a magnetic pole in the vicinity of a head gap.
2. Description of Related Art
FIG. 1(a) is a sectional view of essential parts of the thin-film magnetic head element disclosed in IEEE TRANSACTIONS ON MAGNETICS, Vol. 25, No. 5, September 1989, p. 3190 and FIG. 1(b) is a partially enlarged view in the vicinity of a head gap (b area) shown in FIG. 1(a). In the figure, reference numeral 1 designates an insulative silicon substrate. On the substrate 1, a permalloy core 2a, obtained by laminating a magnetic film 3 for the lower core and a magnetic film 4a for the upper core, is formed. A head gap 6a which forms a magnetic pole generating a recording magnetic field at the permalloy core 2a is provided at the magnetic film 4a for the upper core. The gap length g.sub.L of this head gap 6a is, for example, 0.5 .mu.m. A conductive film 8 as a coil is formed with crossing with the permalloy core 2a. Between the core 2a and the conductive film 8, an insulator 9 is interposed, the insulator 9 insulating the both. At the upper side of the thin-film magnetic head element, a recording medium 10 is disposed which opposes a flying surface 11 of the thin-film magnetic head element in parallel, and moves closely along the thin-film magnetic head element, being apart by a gap d (0.35 .mu.m, for example) therefrom.
Next, explanation will be given on the operation. The thin-film magnetic head is used after being opposed to the recording medium 10 in parallel and moved upward by a gap d. In recording information, information is recorded by flowing current to the conductive film 8 corresponding to the information and magnetizing the recording medium 10 due a to leakage magnetic field generated in the vicinity of the head gap 6a of the magnetic film 4a for the upper core. On the other hand, information is reproduced by moving the magnetized recording medium 10, dividing the magnetic flux of the surface of the recording medium 10 to the magnetic paths of the core 2a, thereby inducing voltage corresponding to the rate of change of the magnetic flux.
In the thin-film magnetic head element as above-mentioned, there is a problem that it is difficult to obtain a recording magnetic field required at a time of recording when trying to make the depth g.sub.D of the head gap 6a shallow in order that reproducing efficiency may be heightened by using much effective magnetic flux crossing the conductive film 8 as a coil among the whole magnetic flux transmitted to the core 2a.